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Ethereum ERC-721 Owner Lookup
x402
Ethereum ERC-721 Owner Lookup is a paid API for AI agents from api.arysphere.com, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-17).
Returns the current owner address of a specific ERC-721 NFT token on Ethereum mainnet given a contract address and token ID.
Price / call$0.003
Success—
StatusUnknown
How this service works
ARYSPHERE sells AI-written verdicts on Base token contracts (a grade, a one-liner, a roast and the contract's facts) and Base/Ethereum chain reads, paid per call in USDC on Base over x402 v2. No account and no API key.
Output
Returns a JSON object with ok status, the chain identifier ('ethereum' or 'base'), the method name ('ownerOf'), and a result object containing the token contract address, the decimal token ID, and the current owner's Ethereum wallet address (0x format).
Example use cases
Verify NFT ownership before transfer
“Before I send payment to this seller, can you confirm that wallet 0x456979e89917f4dc1e86662fcdfd4c9766c6684d actually owns token ID 1001 of the NFT contract 0xa990c6a764b73bf43cee5bb40339c3322fb9d55f on Ethereum mainnet?”
Audit NFT holder for allowlist
“I need to check who currently holds token ID 78 of the ERC-721 contract 0xbc4ca0eda7647a8ab7c2061c2e118a18a936f13d on Ethereum mainnet — we're building an allowlist and need the current owner's address.”
Monitor NFT ownership change
“Can you look up the current owner of token ID 9999 for the ERC-721 contract 0x34d85c9cdeb23fa97cb08333b511ac86e1c4e258 on Ethereum mainnet so I can compare it against who owned it last week?”
Technical details
Endpoint
GEThttps://api.arysphere.com/v1/ventures/x402_eth_reads_v1/eth_mainnet_erc721_ownerof?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you specifically need to resolve the current owner of an ERC-721 NFT on Ethereum mainnet by contract address and token ID. Prefer it over generic blockchain explorers when you need a programmatic, pay-per-call response with a clean JSON structure suitable for agent pipelines. It is distinct from Base network equivalents when Ethereum mainnet ownership data is required.
Side effects
- Invalid contract address format (not 0x + 40 hex) returns a validation error
- Token ID does not exist on the contract returns a revert/not-found error
- Contract address is not an ERC-721 contract returns a call failure
- Network congestion or RPC timeout may cause delayed or failed responses
- Payment of 0.003 USDC not provided or rejected results in 402 Payment Required
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"ok": true,
"chain": "ethereum",
"method": "ownerOf",
"result": {
"id": "1",
"owner": "0x46efbaedc92067e6d60e84ed6395099723252496",
"token": "0xBC4CA0EdA7647A8aB7C2061c2E118A18a936f13D"
},
"service": "x402_eth_reads_v1.eth_mainnet_erc721_ownerof"
}
}Tags
x402
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